The only new encounter on the top floor is with Wyverns and Wyrms, neither of which is anything to worry about. This is a very small floor, and you won't likely be fighting many encounters aside from the Blue Dragon "boss" fight just inside the room with the warp mechanism.
This is a very small floor, and you won't likely be fighting many encounters aside from the Blue D "boss" fight just inside the room with the warp mechanism. You need the CUBE to warp from here to the Floating Castle.